Method for manufacturing a nonwoven product, a nonwoven product obtained in particular by said method and an installation for the manufacture of said nonwoven product

ABSTRACT

A high-quality nonwoven product is manufactured by making use of an intermediate product in which the majority of fibers are distributed in two orientations which form an angle with each other. The intermediate product is fed to a spreading and lap-forming machine (13A, 13B) which deposits the intermediate product in alternate pleats on its delivery belt so as to form a lap of superposed layers such that the majority orientations of the fibers within each layer form an angle with the majority orientations of the fibers of the contiguous layers, and the lap is subjected to a fixing treatment, for example by means of a needle-punching machine (14A, 14B).

The present invention relates to a method for manufacturing nonwovenproducts.

This invention also relates to a nonwoven product which can be obtainedby this method.

The present invention is also concerned with an installation for themanufacture of said nonwoven product.

It is known to manufacture nonwoven fabrics by producing a web oflongitudinal parallel fibers, the web being fed to a spreading andlap-forming machine which forms a lap by depositing said web insuccessive pleats which overlap in a zigzag pattern on a delivery belt,the belt being so arranged as to move at right angles to the directionof feed of the web.

The lap thus obtained has two "privileged" orientations of the fiberswhich correspond to the orientations of the fibers present in superposedweb sections in the lap. These two privileged orientations are usuallysymmetrical with respect to the transverse direction of the deliverybelt and relatively close to this transverse direction.

As a rule, the fibers are then fixed to each other, for example by meansof a needle-punching operation which interlaces the fibers havingdifferent orientations.

There is thus obtained a product having poor uniformity of weight, lowtensile strength in the longitudinal direction since the fibers areessentially directed transversely, and high shrinkage in width at thetime of needle-punching since this operation calls for the applicationof a pulling stress in the longitudinal direction at the exit of theneedle-punching unit.

It is also known to pass fibers successively into two paired units eachconsisting of a card and a spreading and lap-forming machine. This issimply intended to achieve better mixing of fibers which are differentin nature or color but fails to solve the difficulties mentionedearlier.

The object of the present invention is to overcome these difficulties.

In accordance with a first object of the invention, the method formanufacturing a nonwoven product is distinguished by the fact that itinvolves the use of an intermediate product in which the majority of thefibers present therein are distributed in two orientations which form anangle with each other, and that this intermediate product is fed to aspreading and lap-forming unit which deposits the intermediate productin alternate pleats on its delivery belt so as to form a lap ofsuperposed layers such that the majority orientations of the fibers ineach layer form an angle with the majority orientations of the fibers ofthe contiguous layers, and the lap is subjected to a fixing treatment,for example by needle-punching.

Thus the fibers are distributed in four different orientations withinthe lapped product which is accordingly endowed with very gooduniformity and very high tensile strength in all directions. This isadvantageous not only for subsequent treatment but also for themechanical properties of the final product to be obtained.

In accordance with a second object of the invention, the nonwovenproduct is distinguished by the fact that the majority of the fibers insaid product are distributed in four privileged orientations.

In accordance with a third object of the invention, the installation forthe manufacture of a nonwoven product is distinguished by the fact thatit comprises in series, in this order, a card, a first spreading andlap-forming unit, a drawing frame and a second spreading and lap-formingunit.

Other features and advantages of the invention will appear from thefollowing description, taken in connection with non-limiting examples.

In the accompanying drawings:

FIG. 1 is a schematic view of an installation for manufacturing anintermediate product which can be employed in the method in accordancewith the invention.

FIG. 2 is a schematic view in elevation showing the interior of adrawing frame which forms part of the installation of FIG. 1.

FIG. 3 shows in elevation a detail of FIG. 2.

FIGS. 4 to 7 are schematic views showing the privileged orientations ofthe fibers in the textile product at different stages of manufacture.

FIGS. 8 and 9 are schematic views of installations for the manufactureof a finished nonwoven product in accordance with the invention.

An intermediate product employed in the present invention can beobtained by means of the installation shown in FIG. 1 which can formpart of a longer production line as indicated in FIGS. 8 and 9. Thisinstallation comprises, in series, a card 1, a spreading and lap-formingunit 2, a selvedge-teaser 3, a lap-drawing unit 4, and a roller 5 whichcollects the semifinished product.

The card 1 produces a web of fibers 6 having a width L1 (as shown inFIG. 4). The fibers of the web 6 are essentially oriented in a directionwhich is substantially parallel to the longitudinal direction of the web6.

The spreading and lap-forming unit 2 is supplied with said web 6 whichis delivered by the card 1. As shown in FIG. 5, a lap 7 is formed inknown manner by the spreading and lap-forming unit 2 by successivelyfolding the web 6. Said lap 7 is made up of superposed sections of webdelimited by alternate pleats which define the lateral edges of the lap7. These alternate pleats are relatively displaced in a directionparallel to the longitudinal direction X of the lap 7, with the resultthat the majority of the fibers in the lap 7 are distributed in twoorientations D1, D2 which are symmetrical with respect to thelongitudinal direction X of the lap 7. These majority orientations D1,D2 in the lap 7 form with its longitudinal direction X an angle A whichis smaller than 90° and usually fairly close to this value (typically75°<A<90°). This angle A can be chosen in a known manner by adapting theadjustments of the spreading and lap-forming unit 2. In the exampleillustrated in FIGS. 4 and 5, the spreading and lap-forming machine 2has been so adjusted that the lap 7 has four layers of web 6. Thus thesuccessive pleats located on one and the same lateral edge of the lap 7are relatively displaced by one-half the width L1 of the web 6 deliveredby the card 1.

At the exit of the spreading and lap-forming unit 2, the lap 7 passesinto a selvedge-teaser 3 which teases the lateral edges of the lap 7 inknown manner.

At the exit of the selvedge-teaser 3, the lap 7 is introduced into thedrawing frame 4, the exit end of which delivers the intermediate product8 (FIG. 6). As shown in FIG. 2, the lap-drawing frame 4 has rotatingrollers 9, 10 disposed successively along the path of transfer of thelap during the drawing operation. These rollers 9, 10 are placedalternately above and beneath the lap which is being drawn-out. Saidrollers 9, 10 are driven in rotation so as to cause the lap to advancealong the drawing frame 4. Each roller 9, 10 is driven in rotation at aspeed equal to or higher than that of the preceding roller along thepath of travel of the lap. By adjusting the difference in speed betweenthe successive rollers 9, 10 (typically between 0 and 100%), one adjuststhe degree of draft of the lap 7 within the drawing frame 4. The numberof rollers 9, 10 can vary from five to thirty. The total degree of draftcan amount to 800%.

With reference to FIG. 3, it is seen that the rollers 9, 10 are providedat their periphery with a covering in which are set teeth 11. The teeth11 of the covering are flexible. To this end, they can be in the form ofwire teeth fixed on a textile base 12 which surrounds the roller 9, 10.In the example shown in FIG. 3, the flexible teeth 11 extend in asubstantially radial direction with respect to the rollers 9, 10 andhave an end portion which is elbowed (at an angle of 10°, for example)towards the rear with respect to the direction of rotation of the roller9, 10. The teeth 11 carried by two successive rollers 9, 10interpenetrate to a certain length so that, when the lap travels betweenthese two successive rollers, the teeth 11 penetrate to the heart of thelap.

The majority orientations (E1, E2) of the fibers which constitute theintermediate product 8 are shown diagrammatically in FIG. 6. Theorientations of the fibers in the product 8 have been modified by thedrawing operation and the fibers issuing from contiguous sections of webof the non-drawn lap 7 have to some extent been interlocked as a resultof penetration of the teeth 11 into the heart of the lap during thedrawing operation. FIG. 6 illustrates the product 8 made up ofsuccessive inclined sections of web but it will be observed that, forthe sake of enhanced clarity of the figure, this schematic illustrationexaggerates the sharpness of outline of the structure of the product 8which is homogenized by the interengagement of the fibers. Owing to thestructure of the covering of the rollers 9, 10 of the drawing frame 4,the lap is subjected to very slight transverse shrinkage during thedrawing operation, with the result that the width L2 of the drawnintermediate product 8 is substantially equal to that of the lap 7 priorto drawing. The degree of draft within the drawing frame 4 is soadjusted that the fibers within the drawn intermediate product 8 are forthe most part distributed in two orientations E1, E2 which aresubstantially symmetrical with respect to the longitudinal direction Yof the drawn product 8 and form with this direction an angle B withinthe range of 30° to 60°. In the example illustrated in FIG. 6, thedrawing frame 4 has been so adjusted that said angle B is approximately45°, which represents a preferred value for optimizing the homogeneityof the product.

The semifinished product 8 thus obtained has a resistance in thelongitudinal direction which is of the same order of magnitude as theresistance to pulling stress in the transverse direction. If the drawingframe 4 is so adjusted that the degree of draft is increased in order toobtain an angle B of less than 45° between the majority orientations E1,E2 and the longitudinal direction Y, it is possible to obtain a producthaving a resistance to pulling stress (tensile strength) which is higherin the longitudinal direction Y than in the transverse direction.

The semifinished product 8 has sufficient cohesion to be coiled directlyon a roller 5 as it passes out of the drawing frame 4. The semifinishedproduct 8 can thus advantageously be stored in a coiled form.

At the exit of the drawing frame 4, the drawn product 8 can also besubjected to a treatment by heat-setting, water jet, impregnation,needle-punching, incorporation of a chemical binder, spraying,ultrasonic treatment, tufting or sewing of fibers.

The semifinished product 8 advantageously has a weight per unit areawhich is lower than 50 g/m² and preferably lower than 30 g/m². It ispossible for example to obtain a semifinished product 8 having a weightper unit area of 20 g/m² starting from a web 6 of 30 g/m² folded to fourthicknesses so as to form a lap 7 of 120 g/m² prior to drawing.

In accordance with the invention, an intermediate product such as thesemifinished product 8 is employed for the purpose of manufacturing anonwoven fabric which has remarkable mechanical properties. Aninstallation in a non-continuous line which is suitable for thisapplication is shown diagrammatically in FIG. 8, in which the references1 to 5 correspond to the arrangement of machines (as shown in FIG. 1)for the purpose of obtaining the intermediate product. In thisinstallation, the uncoiled semifinished product 8 is introduced into asecond spreading and lap-forming unit 13A, 13B so as to form a secondlap 15 by folding (as shown in FIG. 7). The second spreading andlap-forming unit 13A, 13B deposits the intermediate product 8 inalternate pleats on its delivery belt so as to form a second lap 15 ofsuperposed layers such that the majority orientations of the fibers ineach layer form an angle with the majority orientations of the fibers ofthe contiguous layers. Typically, the second spreading and lap-formingunit 13A, 13B is so arranged as to produce at its exit a second lap 15,the width L3 of which is greater than the width L2 of the semifinishedproduct 8, and the weight per unit area of which is at least equal totwice that of the semifinished product 8. It is apparent from FIG. 7that the majority of the fibers constituting the second lap 15 aredistributed in four distinct orientations F1, F2, F3, F4, thus endowingthe second lap 15 with excellent properties of isotropy. The twomajority orientations F1, F3 in each of the alternate web sectionsconstituting the second lap 15 correspond to the majority orientationsE1, E2 of the fibers in the intermediate product 8 prior to folding. Themajority orientations F1, F3 of the fibers in each layer form an angle Cwith the majority orientations F2, F4 of the fibers of the contiguouslayers. Said angle C can be selected by adjusting the second spreadingand lap-forming unit 13A, 13B in regard to the relative longitudinaldisplacement between two successive pleats along one and the same edgeand the working width.

At the exit of the second spreading and lap-forming unit 13A, 13B, thesecond lap 15 is subjected to a fixing treatment, for example by meansof a needle-punching machine 14A, 14B. The needle-punched nonwovenproduct obtained at the exit of the needle-punching unit 14A, 14B hasfibers distributed for the most part in the four privileged orientationsF1, F2, F3, F4 of the second lap 15. This product has values of breakingstrength and of elongation at rupture which can be adjusted by adaptingthe number of pleats made in the second spreading and lap-forming unit13A, 13B, these values being substantially equal to each other in thelongitudinal and transverse directions of the nonwoven product.

Since the intermediate product 8 is passed through a selvedge-teasingunit 3 prior to drawing, the lateral edges of the intermediate product 8are practically invisible on the final needle-punched nonwoven product.

It is apparent from FIG. 8 that two groups 13A, 14A and 13B, 14B eachconsisting of a spreading and lap-forming machine and a needle-punchingmachine are mounted downstream of the same drawing frame 4. The objectof this arrangement is to optimize the use of these machines since theoutput of the drawing frame 4 is usually higher than the input of aspreading and lap-forming machine 13A, 13B. This advantageousarrangement can be obtained by virtue of the fact that the intermediateproduct 8 can be coiled at the exit of the drawing frame 4, thenuncoiled at the entrance of one of the spreading and lap-forming units13A, 13B.

As will be readily understood, if the above-mentioned input and outputare adjusted so as to be relatively close in value, a single groupformed by a spreading and lap-forming machine and a needle-punchingmachine can be mounted directly at the exit of the drawing frame 4 andthe storage roller 5 may accordingly be dispensed with.

This installation operates in a continuous production line and isillustrated diagrammatically in FIG. 9. Three main differencesdistinguish this installation from that illustrated in FIG. 8:

1) a single group consisting of a spreading and lap-forming machine anda needle-punching machine 13, 14 is mounted downstream of the drawingframe 4;

2) the storage roller 5 is dispensed with and the spreading andlap-forming unit 13 is directly supplied with intermediate product;

3) the positions of the drawing frame 4 and of the selvedge-teasing unit3 are reversed (as a rule, the selvedge-teaser 3 can be placedindifferently upstream or downstream of the drawing frame 4, the purposeof this unit being to prevent the edges of the intermediate product fromappearing on the final nonwoven product).

It will therefore be understood that the method in accordance with theinvention can be carried out either non-continuously by means of aninstallation as illustrated in FIG. 8, in which case the intermediateproduct 8 is temporarily stored after drawing, or continuously by meansof an installation as illustrated in FIG. 9, in which case theintermediate product 8 has only a brief existence, between the exit ofthe drawing frame 4 and the entrance of the spreading and lap-formingunit 13, thus avoiding any risk of modification of its properties duringstorage.

As will be readily understood, any number of modifications can be madein the particular examples described in the foregoing without therebydeparting from the scope of the present invention.

We claim:
 1. A method of manufacturing a nonwoven product from asemifinished nonwoven product (8), comprisingproviding discontinuousfibers to a card (1); producing a carded web (6) from said fibers;delivering said web (6) from the card (1) in a longitudinal directionwith the majority of the discontinuous fibers within the web (6)distributed in a direction parallel to said longitudinal direction;feeding said web (6) to a cross-lapping unit (2); folding the web (6)into the cross-lapping unit (2) so as to obtain a batt (7) having aselected width (L2) as measured perpendicularly to said longitudinaldirection (Y) and including a selected number of layers from thecross-lapped web (6), the majority of the discontinuous fibers in thebatt (7) being distributed in two directions (D1; D2) that aresymmetrical and are oriented at a first angle (A) comprised between 75°and 90° to a longitudinal direction (X) of the batt (7) delivered by thecross-lapping unit (2); feeding the batt (7) to a drawing frame (4)including two series of rollers (9, 10) rotated with an increasingvelocity in the longitudinal direction and each covered with flexiblymounted needle-like teeth (11), the teeth (11) of said series of rollers(9, 10) radially inter-fingering with each other; passing the batt (7)between the rollers in such a manner that the teeth (11) of the rollerspenetrate the batt (7) which is thus drawn to obtain a semifinishednonwoven product (8), the degree of drawing being such that over thewhole thickness of the product (8) the majority of the discontinuousfibers are pivoted about the teeth (11) in such a manner that said firstangle (A) is changed to a second angle (B) comprised between 30° and 60°to the longitudinal direction (Y) of the two symmetrical directions (E1;E2) of the majority of the discontinuous fibers in the drawn product(8); said second angle (B) being such as to obtain a predeterminedresistance to pulling stress of the drawn product (8); and a width (L2)of the product (8) as measured perpendicular to the longitudinaldirection (Y) is substantially equal to the corresponding width (L2) ofthe batt (7) before drawing; feeding said semifinished intermediateproduct (8) to a spreading and lap-forming unit (13; 13A; 13B) whichdeposits the semifinished product (8) in alternate pleats on a deliverybelt of the lap-forming unit, so as to form a lap (15) of superposedlayers such that the majority of the discontinuous fibers in each layerare distributed in orientations (F1; F3) forming an angle (C) with theorientations (F2; F4) of the majority of the fibers in the contiguouslayers; and subjecting the lap (15) subsequently to a fixing treatmentin order to obtain a nonwoven product presenting four differentorientations (F1; F2; F3; F4) of the majority of the discontinuousfibers.
 2. A method as claimed in claim 1, wherein said second angle (b)is about 45°.
 3. A method as claimed in claim 1, wherein said batt (7)is comprised of four layers of web.
 4. A method as claimed in claim 1,and subjecting the edges of said batt (7) to teasing.
 5. A method asclaimed in claim 1, and coiling said semifinished woven product (8), andthen uncoiling said semifinished unwoven product (11) prior to feedingthe same to said lap forming unit (13; 13A; 13B).
 6. A method as claimedin claim 1, wherein said fixing treatment is needle punching.
 7. Aninstallation for manufacturing a nonwoven product from a semifinishednonwoven product (8), comprisingmeans for providing discontinuous fibersto a card (i); means for producing a carded web (6) from said fibers;means for delivering said web (6) from the card (1) in a longitudinaldirection with the majority of the discontinuous fibers within the web(6) distributed in a direction parallel to said longitudinal direction;means for feeding said web (6) to a cross-lapping unit (2); means forfolding the web (6) into the cross-lapping unit (2) so as to obtain abatt (7) having a selected width (L2) as measured perpendicularly tosaid longitudinal direction (Y) and including a selected number oflayers from the cross-lapped web (6), the majority of the discontinuousfibers in the batt (7) being distributed in two directions (D1; D2) thatare symmetrical and are oriented at a first angle (A) comprised between75° and 90° to a longitudinal direction (X) of the batt (7) delivered bythe cross-lapping unit (2); means for feeding the batt (7) to a drawingframe (4) including two series of rollers (9, 10) rotated with anincreasing velocity in the longitudinal direction and each covered withflexibly mounted needle-like teeth (11), the teeth (11) of said seriesof rollers (9, 10) radially interfingering with each other; means forpassing the batt (7) between the rollers in such a manner that the teeth(11) of the rollers penetrate the batt (7) which is thus drawn to obtaina semifinished nonwoven product (8), the degree of drawing being suchthat over the whole thickness of the product (8) the majority of thediscontinuous fibers are pivoted about the teeth (11) in such a mannerthat said first angle (A) is changed to a second angle (B) comprisedbetween 30° and 60° to the longitudinal direction (Y) of the twosymmetrical directions (E1; E2) of the majority of the discontinuousfibers in the drawn product (8); said second angle (B) being such as toobtain a predetermined resistance to pulling stress of the drawn product(8); and a width (L2) of the product (8) as measured perpendicular tothe longitudinal direction (Y) is substantially equal to thecorresponding width (L2) of the batt (7) before drawing; means forfeeding said semifinished intermediate product (8) to a spreading andlap-forming unit (13; 13A; 13B) which deposits the semifinished product(8) in alternate pleats on a delivery belt of the lap-forming unit, soas to form a lap (15) of superposed layers such that the majority of thediscontinuous fibers in each layer are distributed in orientations (F1;F3) forming an angle (C) with the orientations (F2; F4) of the majorityof the fibers in the contiguous layers; and means for subjecting the lap(15) subsequently to a fixing treatment in order to obtain a nonwovenproduct presenting four different orientations (F1; F2; F3; F4) of themajority of the discontinuous fibers.
 8. An installation as claimed inclaim 7, wherein said second angle (b) is about 45°.
 9. An installationas claimed in claim 7, wherein said batt (7) is comprised of four layersof web.
 10. An installation as claimed in claim 7, and means forsubjecting the edges of said batt (7) to teasing.
 11. An installation asclaimed in claim 7, and means for coiling said semifinished wovenproduct (8), and then means for uncoiling said semifinished unwovenproduct (11) prior to feeding the same to said lap forming unit (13;13A; 13B).
 12. An installation as claimed in claim 7, wherein saidfixing treatment is needle punching.